1. Field of the Invention
This invention relates to a device suitable for clarifying sewage containing organic matter, such as industrial waste water and living waste water, and more particularly to a clarification device of contact aeration type which is easy to inspect and repair.
2. Description of the Prior Art
One purifier of contact aeration type is known which comprises a purifier tank having an opening at its top and including an inlet and an outlet adjacent to the opening for sewage, at least one contact member disposed in the purifier tank, at least one air-flowing pipe disposed at the bottom of the purifier tank, and a closure for closing the opening. In this type of purifier, inspections are to be conducted on the opening condition of the air flowing pipe as well as on the condition in which the contact members are choked up due to growth of microorganisms attached to the contact members, then the purifier is repaired if necessary.
A problem with this prior art purifier is that since a space is provided in the purifier tank and filled with the contact members including contact material, such as small stones and foamed plastic material, it is necessary to remove all the contact members from the purifier tank, or the worker must step into the bottom of the purifier tank in order to inspect and repair the air-flowing pipe (if the latter is disposed below the contact members), which are laborious.
Further, generally in the prior art purifier, the closure covering the opening of the purifier tank is fixed to the tank and is provided with a manhole for maintenance and care. With this prior arrangement, if the contact members are large in size, the closure must be broken to take the contact members out of the tank. Yet, if the contact members are small in size, they are necessarily large in number, which takes a long time to take them out of the tank.